In caring for pregnant women, the physician must consider the health of two patients who are biologically linked, yet individually viable. Although most pregnant women willingly accept some risk to their own health in order to optimize fetal outcome, occasionally women refuse treatment recommended for their fetus. When a pregnant woman refuses medical therapy which could be life-saving for her fetus, complicated ethical issues arise.

Advances in medical technology have increased the physician's ability to direct medical procedures towards the fetus. Previously, physicians conceptualized the maternal-fetal dyad as one complex patient. Viewed as an organic whole, the combined maternal and fetal benefits of a proposed therapy could be weighed against the combined burdens. Distribution of benefits and burdens between the fetal and maternal components of the one patient was not ethically relevant. Over time, the medical model for the maternal-fetal relationship has shifted from unity to duality. When there are two individual patients, the physician must decide what is medically best for each patient separately.

Fetal care becomes problematic when what is required to benefit one member of the dyad will cause an unacceptable harm to the other. When a fetal condition poses no health threat to the mother, caring for the fetal patient will always carry some degree of risk to the mother, without direct therapeutic benefit for her. The ethical principles of beneficence ("be of benefit") and nonmaleficence ("do no harm") can come into conflict.

Because the patients are biologically linked, both, or neither, must be treated alike. It would be unethical to recommend fetal therapy as if it were medically indicated for both patients. Still, given a recommendation for fetal therapy, pregnant women, in most cases, will consent to treatment which promotes fetal health. When pregnant women refuse therapy, physicians must remember that the ethical injunction against harming one patient in order to benefit another is virtually absolute.

Some ethicists purport that viability entitles the fetus to "moral personhood". Viability is the physical capacity for life independent of maternal corporeal support. They argue that newborns and fetuses participate in the social matrix, and that this social role develops over time, beginning prior to birth. Others note that it is impossible to treat fetuses as persons without treating pregnant women as if they were less than persons. The birth of the fetus results in a distinct patient towards whom medical therapy can be individually directed. As such, many believe that the moral status of a developmentally younger newborn supersedes that of an older viable fetus.

Throughout the world, the legal status of fetuses is generally subordinated to that of pregnant women. In most countries, the legal status of the fetus is bolstered as gestation progresses. Viability signifies a change in its legal status. Still, although the human fetus has the potential for personhood, this does not imply that it is a person or that it has rights. So long as the fetus is attached to the pregnant woman, her body maintains its life, and bars access to it.

US courts have ruled that a child has a legal right to begin life with a sound body and mind. Such a right may create a legal duty, on the part of a pregnant woman, to protect the health of her fetus. Failure to fulfill that duty could subject her to charges of fetal abuse, or render her liable for consequent damage to her child. Pregnant women's refusals of hospitalization, intrauterine transfusion, or surgical delivery have been legally challenged on the grounds of an obligation to the fetus.

Parents are granted wide discretion in making decisions about their children's lives. However, when the exercise of certain beliefs would disadvantage the child's health in a serious way, there are limits in exercising this discretion (for further discussion, see the pediatric portion of the Cross-Cultural Issues topic page).

US courts have demonstrated a willingness to force treatment on a mother for the sake of her viable fetus. However, the decisions of lower-court judges do not necessarily reflect settled law. Of the two court orders that have been reviewed by the highest courts of their respective states, one was upheld and the other was overruled.

The use of court orders to force treatment on pregnant women raises many ethical concerns. Court orders force pregnant women to forfeit their autonomy in ways not required of competent men or nonpregnant women. There is an inconsistency in allowing competent adults to refuse therapy in all cases but pregnancy. Hospital administrators, lawyers and judges have little warning of impending conflicts and little time for deliberation; this time pressure makes it unlikely that pregnant women will have adequate legal representation. Furthermore, forced obstetrical interventions have the potential to adversely affect the physician-patient relationship. The American College of Obstetrics and Gynecology has stated that "Obstetricians should refrain from performing procedures that are unwanted by pregnant woman....The use of the courts to resolve these conflicts is almost never warranted."